Diesel pile hammer

ABSTRACT

The invention relates to a diesel pile hammer ( 10 ) which comprises a cylinder ( 12 ), a piston ( 14 ) slidably mounted inside the cylinder ( 12 ), and an impact piece ( 16 ) slidably mounted inside the cylinder ( 12 ), said impact piece being arranged below the piston ( 14 ) in the operating position of the diesel pile hammer ( 10 ). A working compartment ( 32 ) is axially delimited by a face ( 36 ) of the impact piece ( 16 ) lying inside the cylinder ( 12 ) and a face ( 46 ) of the piston ( 14 ). A fuel supply device ( 52, 55, 62, 68 ) feeds a defined amount of fuel, especially diesel oil, to said working compartment with every working cycle. The fuel supply device ( 52, 55, 62, 68 ) is configured to inject the fuel into the working compartment ( 32 ) of the cylinder ( 12 ) optionally in a first mode of injection as an atomized fuel spray ( 76 ) or in a second mode of injection as a fuel jet ( 74 ) or in a third mode of injection both as an atomized fuel spray ( 76 ) and as a fuel jet ( 74 ).

The invention relates to a diesel pile hammer comprising

(a) a cylinder,

(b) a piston slidably guided in the cylinder,

(c) an impact piece that is slidably guided in the cylinder and in the operating position of the diesel pile hammer is arranged below the piston,

(d) a working compartment which is axially delimited by an end face, located inside the cylinder, of the impact piece and an end face of the piston,

(e) a fuel supply device through which a predefined amount of fuel, in particular diesel oil, can be introduced into the working compartment with every working cycle.

Diesel pile hammers of this type, which are also called diesel rams, are used in particular in foundation working in the building industry to drive home all kinds of piles, such as concrete piles, iron girders, sheet piling elements or the like, into a subsoil.

To start a diesel pile hammer of this type the piston is pulled upwards with the aid of a release device and is released at a specific height, whereupon it drops down under the influence of gravity. On dropping, the piston actuates a fuel pump, whereby one or more injection nozzle(s) is/are supplied with fuel, in particular diesel oil, which nozzles inject the fuel into the working compartment of the cylinder.

As the piston drops the air situated in the working compartment of the cylinder is compressed and consequently heated in such a way that the fuel/air mixture present in the working compartment ignites, whereupon it combusts in the manner of an explosion.

The explosive energy released in the process on the one hand throws the piston upwards again for a new working cycle and on the other hand drives the piling into the ground.

Two types of diesel hammer with different modes of fuel injection into the working compartment are known in the case of diesel pile hammers of this kind.

In the case of a first mode of injection—high-pressure injection—the fuel is injected, usually in the form of a finely atomised fuel mist, at high pressure into the working compartment of the cylinder during compression of air by the dropping piston. This mist, together with the air, forms an ignitable mixture. In the case of high-pressure injection the fuel ignites as early as during the compression process and as soon as the compressed air reaches a temperature which is sufficient to ignite the fuel mixture.

The explosive combustion causes a high pressure to build in the working compartment, via which on the one hand the piston is decelerated and on the other hand this combustion pressure acts on the impact piece which exerts a force on the piling, whereby the piling is driven into the ground.

The compression process ends, at the latest, when the piston strikes the impact piece, wherein the piston, which has already been decelerated by the expanding combustion products before the impact piece is struck, does not strike the impact piece with all of its kinetic energy. Occasionally, in particular in the case of a hard subsoil, the situation may even occur where the piston does not touch the impact piece at all and, without prior contact with the impact piece, is thrown upwards again by the combustion gases. Under conditions of this kind the impact piece acts on the piling only by way of the combustion gas cushion.

Diesel pile hammers in which a high-pressure injection is used are therefore less suitable for driving home heavy piling or in the case of difficult ground conditions with hard layers.

In addition, a diesel pile hammer of this kind becomes very hot during operation and the system of high-pressure injection has a tendency to misfire in the event of over-heating. A system of this kind is moreover susceptible to repair and has a relatively complicated construction. This brings with it the drawback that a diesel pile hammer with high-pressure injection can be only poorly repaired, or not repaired at all, in situ on building sites.

Advantages of high-pressure injection lie in good, relatively residue-free combustion and good starting behaviour of the diesel pile hammer as well as a good is pile-driving effect with soft ground layers.

The second type of mode of injection is what is known as impact atomisation, which, in contrast to high-pressure injection, can also be called low-pressure injection.

In this case the fuel is introduced, usually in the form of a fuel jet, at low pressure into the working compartment at the start of the compression process and thereafter first of all rests as an area of fuel on the upper end face of the impact piece.

The air in the working compartment is compressed by the dropping piston until the piston strikes the impact piece. At this instant the liquid fuel is atomised by the striking piston face and fin this state ignites in the hot, compressed air. The piston is then thrown upwards by the explosion, whereupon a further working cycle can begin.

Until it strikes the impact piece the piston's descent is decelerated only by the air that is situated in the working compartment and which it compresses. This means the kinetic energy of the piston is largely transferred to the impact piece, whereby, with the same piston weight, much higher impact forces can be exerted on the piling than is the case with the above-described high-pressure injection. The impact of the piston on the impact piece takes place before combustion of the fuel.

Diesel pile hammers which use low-pressure injection are less suitable for use with low ground resistances. In these cases the compression is reduced owing to the lower resistance of the ground, since the decreasing compressive pressure is already transferred to the piling via the downward-moving impact piece. The working compartment is factually enlarged thereby, and this, in turn, is at the expense of the compressive pressure.

Combustion is thus of only reduced quality in the case of soft ground, and this can lead to undesirable residues (carbon block, unburned fuel in the combustion gases) which burden the environment.

One advantage of impact atomisation is that the kinetic energy of the piston is effectively used since the piston strikes the impact piece with force. In addition a diesel pile hammer with impact atomisation has less of a tendency to overheat, is less susceptible to faults and is easier to control than a diesel pile hammer with high-pressure injection.

Previously the drawback that a diesel pile hammer operating according to one of the two operating principles could only ever take account of specific local circumstances had to be accepted in the case of diesel pile hammers. If in situ it turned out that the quality of the ground was or would be different than planned, either work had to be continued using the apparatus that was not optimal or a different diesel pile hammer had to be acquired, and this led to lost time and higher costs.

The aim of the invention is to create a diesel pile hammer which can be used in different ground conditions with good impact effectiveness and good quality of combustion at the same time.

This object is achieved with a diesel pile hammer of the type discussed in the introduction in that:

-   -   (f) the fuel supply device is constructed in such a way that the         fuel is injected into the working compartment in a first mode of         injection as an atomised fuel mist and in a second mode of         injection as a fuel jet.

This makes it possible for the diesel pile hammer to operate in soft ground conditions with high-pressure injection but in the case of hard ground layers may be operated using the above-discussed impact atomisation.

Adjustment of the effectiveness of the diesel pile hammer, with simultaneous optimisation of combustion, which also partially depends on the ground resistance, to soft or hard ground layers is thus ensured.

It is advantageous if the fuel mist of the first mode is of injection flows into the working compartment in the vicinity of the upper end face of the impact piece substantially vertically to the direction of movement of the piston. This achieves good distribution of the fuel mist in the working compartment, and this leads to good and effective combustion of the resulting fuel/air mixture overall.

The fuel jet of the second mode of injection is advantageously injected into the working compartment of the cylinder in such a way that it obliquely strikes the piston-side end face of the impact piece. This ensures that the liquid fuel is well distributed over the end face, and this leads to improved atomisation when the piston strikes the impact piece, and therewith to good and effective combustion.

A diesel pile hammer that is easy to implement in terms of construction is produced by the embodiment in which the fuel supply device comprises at least one high-pressure injection nozzle and at least one low-pressure injection nozzle, to which via one pipe in each case and by way of at least one fuel pump, of which the inlet communicates with a fuel tank, a specific amount of fuel can be supplied with every working cycle of the diesel pile hammer.

Already known components of a high-pressure injection or a low-pressure injection can thus advantageously be used to achieve a diesel pile hammer according to the invention.

It is advantageous if the amount of fuel supplied via a high-pressure injection device in each case and the amount of fuel supplied via a low-pressure injection device in each case is adjustable, preferably via the fuel pump itself. The impact intensity of the diesel pile hammer can be adapted to different ground conditions as a result, depending on the hardness of the subsoil.

Alternatively use of controllable regulators or valves that can be controlled in terms of their opening time is also possible.

An injection of fuel that functions well and is reliably adapted to a working cycle of the diesel pile hammer in terms of time is achieved if the dropping piston controls or actuates the fuel pump or an injection valve.

Clogging of the usually very fine injection nozzles of the high-pressure injection device is easily prevented if the fuel pump of the high-pressure injection device supplies a minimum amount of fuel with every working cycle. Fuel consequently flows through the injection nozzle with every cycle and the nozzle is thus liberated or kept free of impurities.

A combustion chamber that ensures effective combustion is given if the end face of the piston delimiting the working compartment of the cylinder is stepped by a circumferential radially external step. The combustion chambers which is formed if the end face of the piston rests on the inner end face of the impact piece, is thus toroidal and has a relatively low volume.

According to a further development of the invention it is provided that in a third mode of injection the fuel is injected into the working compartment of the cylinder as both an atomised fuel mist and as a fuel jet.

A transition between the first and second mode of injection can thus be achieved.

Embodiments of the invention will be described in more detail hereinafter with reference to the drawings, in which:

FIG. 1 shows partially in section, a lower portion of a diesel pile hammer that faces the subsoil,

FIGS. 2 and 3 show a low-pressure injection device with fuel pump, of which the actuating ram is shown in different starting positions, and

FIG. 4 schematically shows an electronic controller of the amount of fuel which is supplied to the working compartment.

FIG. 1 shows a diesel pile hammer 10 with a cylinder 12, open on both sides, which in practice can have a length of 5 to 10 m and a diameter of 0.5 to 1 m.

A piston 14 runs in the cylinder 12. An impact piece 16 that is coaxial thereto slidably engages in the open, lower end of the cylinder 12. The lower end of the cylinder 12 carries an annular bearing unit 20 that is secured by means of screws, of which one is identified by reference numeral 18 in the figure. A central shaft portion 22 of the impact piece 16 is tightly and slidably guided in this bearing unit and has an external diameter which is reduced compared with the internal diameter of the cylinder 12.

Formed on the lower end of the shaft portion 22 is an impact plate 24, located below the cylinder, of which the outer, lower, convex delimiting face 26 cooperates during operation with the upper end of a piling that is to be driven home, such as a concrete pile, an iron girder, a sheet piling element or the like.

Formed on the upper end of the shaft portion 22 of the impact piece 16 is a piston portion 28 with a plurality of circumferential, axially spaced-apart sealing rings 30 which run on the inner circumferential surface 32 of the cylinder 12. The upper side of the piston portion 28, together with the lower side of the piston 14 and the circumferential wall of the cylinder 12, delimits a working compartment 34. The end face 36 of the impact piece 16 that faces the working compartment 34 of the cylinder 12 is surface ground with a flat fuel depression 37.

A damping ring 38 is arranged between the impact plate 24 of the impact piece 16 and the bearing unit 20 of the cylinder 12. A further damping ring 40 is effective in the vicinity of the bearing unit 20 between the upper side of the bearing unit 20 and the lower side of the piston portion 28 of the impact piece 16.

A lower working end 44 of the piston 14, which is provided with circumferential, axially spaced-apart sealing rings 42, runs inside the cylinder 12 above the impact piece 16.

The lower, free, flat surface ground end face 46 of the piston 14 is stepped by a radially external, circumferential step 48, forming a toroidal-shaped combustion chamber if the end face 46 of the piston 14 rests on the end face 36 of the impact piece 16.

The working end 44 of the piston 14 is formed on a mass portion 50 thereof which extends into the upper portion (not shown here) of the cylinder 12.

To raise the piston 12 to start the diesel pile hammer for the first time the mass portion 50 has a driving shoulder (not shown here) on which a releasable hook of a lifting device (not shown here either) can act.

A high-pressure injection device 52 with a schematically indicated fuel pump 53 and a high-pressure injection nozzle 54 is arranged on the circumferential wall of the cylinder 12. In the upper end position, shown in the figure, of the impact piece 16 the injection nozzle 54 of the high-pressure injection device 52 opens into the working compartment 34 of the cylinder 12 just above the end face 36 of the impact piece 16 if, in other words, an upper annular face 56 of the impact plate 24 of the impact piece 16 rests against the damping ring 38.

In addition to the high-pressure injection nozzle 54 further high-pressure injection nozzles may be arranged (preferably at the same level) so as to be distributed in the circumferential wall of the cylinder 12.

The high-pressure injection nozzle 54 is connected to the outlet of the fuel pump 53 arranged on the outside of the cylinder 12 via a pipe 58, the inlet of the fuel pump communicating with a fuel tank 55 filled with diesel oil. The fuel pump 53 is actuated via an actuating ram 57 if the piston 14 drops downward.

The high-pressure injection device 52, in particular the injection nozzle 54 thereof, is constructed in such a way that it injects the diesel oil supplied to it at high pressure into the working compartment 34 of the cylinder 12 substantially as finely atomised mist 76. The injection nozzle 54 is in the process oriented in such a way that the diesel oil is injected substantially vertically to the movement direction of the piston 14.

A further fuel pump 60, which is driven by an actuating ram 61 that is pre-tensioned into the interior of the cylinder 12 when the piston 14 drops, is connected at the delivery side by a pipe 64 to a low-pressure injection nozzle 66 and forms therewith a low-pressure injection device 68. The fuel pump 60 communicates with a fuel tank 62 filled with diesel oil. The low-pressure injection device 68 is provided on and in the circumferential wall of the cylinder 12 so as to be axially spaced apart from the high-pressure injection device 52 in the direction of the upper end of the cylinder 12. Its injection nozzle 66 is constructed and oriented in such a way that the delivered fuel is injected in a substantially continuous jet approximately centrally onto the end face 36 of the impact piece 16.

Supplementary, further low-pressure injection nozzles, preferably located at the same height as the low-pressure injection nozzle 66, may also be distributed over the circumference of the cylinder 12 in this case as well.

Overall the high-pressure injection device 52, the low-pressure injection device 68 and the fuel tanks 55 and 62 therefore together form a fuel supply device.

The fuel pumps 53 and 60 can be adjusted independently of each other in terms of their delivery, so the fuels supplied to the high-pressure injection nozzle 54 and the low-pressure injection nozzle 66 is continuously variable, as will be described hereinafter.

Above the low-pressure injection device 68 the circumferential wall of the cylinder 12 is penetrated by obliquely upwardly extending working connecting pieces 70 and 72, as may be seen from the figure. Combustion air is drawn in and combustion gases are released via these connecting pieces.

Finally the diesel pile hammer 10 comprises lubricant pumps (not shown separately here) and lubricant nozzles distributed in the circumferential direction of the cylinder 12, via which lubricant is delivered between the piston 14 and the inner circumferential surface 32 of the cylinder 12.

FIGS. 2 and 3 show the fuel pump 60 of the low-pressure injection device 68, wherein its actuating ram 61 is shown in two different starting positions.

The actuating ram 61 extends through the circumferential wall of the cylinder 12. It ends at the outside in a pump ram 80 and inside the cylinder 12 in a wedge-shaped actuating portion 82 running in an appropriate recess 81 in the circumferential wall of the cylinder 12, the ram and actuating portion being connected to each other by a piston rod 84. A concave actuating face 86 of the actuating portion 82 that points toward the interior of the cylinder 12 has a curvature which matches that of the inner circumferential surface 32 of the cylinder 12 and is upwardly and radially outwardly inclined.

Depending on the starting position of the actuating ram 61, the actuating surface 86 thereof projects completely, as may be seen in FIG. 2, or with a lower region, and this may be seen in FIG. 3, into the interior of the cylinder 12.

Approximately centrally between the pump ram 80 and the actuating portion 82 an upwardly pointing stop plate 88 is connected to the piston rod 84 and cooperates with a radially adjustable stop plate 90, secured to the housing, of a stroke-adjusting device 92. The stop plate 90 runs across a threaded hole 94 on a radially outwardly extending threaded spindle 96, which can be rotated by a servomotor 98 which is only schematically indicated in the drawings.

The pump ram 80 runs in a pump cylinder 100, arranged on the outside of the circumferential wall of the cylinder 12, the pump cylinder comprising a fuel outlet 102, which communicates with the injection nozzle 66, and a fuel outlet 104, which is fluidically connected to the fuel tank 62.

The actuating ram 61 is pressed by a spring 106 always in the direction of the interior of the cylinder 12, so in the starting position the stop plate 88 rests against the stop plate 90 of the stroke adjusting device 92.

FIG. 2 shows the position of the stop plate 90 in which the pump piston 80 has its greatest stroke. This means that in this position of the stop plate 90 the amount of fuel delivered per stroke by the fuel pump 60 is the maximum.

If accordingly, starting from the position shown in FIG. 2, the threaded spindle 96 rotates the adjusting device 92, the sop plate 90 is moved radially outwards. The stroke of the pump ram 80 in the pump cylinder 100 is reduced thereby, and therewith the volume of the working compartment 108 of the fuel pump, and this thus leads to a reduction in the amount of fuel which can be delivered per stroke. FIG. 3 shows such a position of the stroke adjusting device 92.

The high-pressure injection device 52 can be constructed so as to correspond with the above-described embodiment of the low-pressure injection device 68. Components of the high-pressure injection device 52 are provided with corresponding reference numerals in FIGS. 2 and 3.

The amount of fuel delivered into the working compartment 32 of the cylinder 12 by the high-pressure injection device 52 or by the low-pressure injection device 68 can consequently be predetermined by the respective position of the associated stop plate 90 secured to the housing.

FIG. 4 shows an electronic controller for the amount of fuel supplied to the working compartment 32 of the cylinder 12, wherein components corresponding to those in FIGS. 1 to 3 are identified by the same reference numerals.

The high pressure injection nozzle 54 and the low-pressure injection nozzle 66 are each fluidically connected to a spring-loaded solenoid valve 110. The valves communicate with one pressurised fuel accumulator 112 respectively which is fed by the corresponding fuel pumps 53 and 60 via non-return valves 113.

The amount of fuel which is to be supplied to the high-pressure injection nozzle 54 and the low-pressure injection nozzle 66 is input into a computer 114 with a display monitor 116 via a keypad 118. Information about the present ground conditions is also possible as input parameters, with the aid of which data adapted by appropriate software is then calculated for the high-pressure injection device 52 and the low-pressure injection device 68.

From the input data the computer 114 calculates the period over which the solenoid valves 110 are open, whereby a specific amount of fuel is injected through the high-pressure injection nozzle 54 or through the low-pressure injection nozzle 66 into the working compartment 32 of the cylinder 12 according to the opening time of the valves.

The opening times determined by the computer are transmitted to a control unit 120 which forwards these as control signals to a controllable monostable 122 of the high-pressure injection device 52 or the low-pressure injection device 68 respectively.

At the input-side the monostables 122 are connected via contact terminals 124 to actuating rams 126 that project into the path of the piston shown only schematically in FIG. 4 and are activated by a movement of the actuating ram 126. Alternatively sensors that operate contactlessly can be used which respond if the piston 14 reaches a predefined position on dropping.

At the output side the monostables 122 are each connected to an amplifier 128 which guides the amplified signal of the monostable 122 to the corresponding solenoid valve 110, whereupon the valve adopts its open position corresponding to the respectively adjusted pulse width of the monostable 122. If the switching time of the two monostables 110, which can be selected so as to be different for the high-pressure injection device 52 and the low-pressure injection device 68, is attained the solenoid valves 110 are transferred into their closed position again by spring force.

A solenoid valve 110, a fuel reservoir 112 and a monostable 122 combined thus form a fuel source of which the delivery can be controlled.

The above-described diesel pile hammer 10 works as follows:

In the starting state the piston 12 is raised by the holding device, already discussed but not shown, into an upper position. After release it drops downwards from the raised position under the effect of gravity, closes the working connecting pieces 70 and 72 and with its end face 46 actuates the actuating ram 57, 61 of the high-pressure injection device 52 or the low-pressure injection device 68.

If the embodiment of the injection devices 52 and 68 shown in FIGS. 2 and 3 is used, this means that the piston 14 strikes the actuating face 86 of the actuating portion 82 of the actuating ram 61 from above. As the piston 14 continues to drop the ram is displaced, to the left in FIGS. 2 and 3. The pump ram 80 is displaced in the direction of the outlet 102 of the pump cylinder 100 as a result, whereby the fuel in the working compartment 108 is conveyed to the injection nozzle 54 or 66 and injected into the working compartment 34 of the cylinder.

An ignitable mixture of fuel droplets and air forms in the working compartment 34, be it as a result of the high-pressure injection or impact atomisation. The injection nozzles 56 and 66 will accordingly inject a specific amount of diesel oil into the working compartment 34 of the cylinder 12 in the above-described manner respectively, individually or in combination, depending on the setting of the fuel pumps 53 and 60. If one of the injection devices 52, 68 should not inject fuel into the working compartment 34 of the cylinder 12, by controlling the servomotor 98 its actuating ram 57 or 61 is radially outwardly displaced until the respective actuating portion 86 no longer projects into the interior of the cylinder 12.

When using an electronic controller, which is shown in FIG. 4, the desired parameters are programmed via the computer 114. If one of the two injection devices 52, 68 should not inject fuel into the working compartment 34 of the cylinder 12, the corresponding monostable 122 is controlled to pulse width zero in this case, so the corresponding solenoid valve 110 is not opened when the piston 14 drops.

When the piston 14 strikes the impact piece 16 and/or across the gas cushion between piston and impact piece, a downwardly directed force is exerted on the impact piece, and via the impact piece on the piling, which drives the piling further into the ground.

During the subsequent upwards movement of the piston 14, triggered by the explosive combustion of the diesel oil, the piston releases the working connecting pieces 70, 72, whereby the combustion gases expand and flow off via the working connecting pieces 70, 72. The piston 14 is accordingly thrown further upwards while drawing in fresh combustion air, and this likewise takes place via the working connecting pieces 70, 72, until it reaches its upper end position and repeats the described working cycle.

The diesel pile hammer can therefore optionally be operated only by means of the high-pressure injection device 52 in a first mode of injection as atomised fuel mist, only by means of the low-pressure injection device 68 in a second mode of injection as a fuel jet or by a combination of these two in a third mode of injection as both atomised fuel mist and fuel jet. It may be adjusted to different ground conditions thereby.

Soft ground conditions, i.e. low ground resistance, usually occur at the start of a driving-home operation, whereby it is advantageous to operate the diesel pile hammer 10 only or predominantly with high-pressure injection 52 at this time. The low-pressure injection device 68 can optionally also be supplied with a small amount of fuel, so the impact atomisation already mentioned is also used by way of assistance.

If the piling reaches more load-bearing and therewith usually harder layers of the ground, the proportion of low-pressure injection can he increased by appropriate modification of the allocated amount of fuel via the low-pressure injection device 68, whereby the direct force transmission of the piston 14 to the impact piece 16 and therewith to the piling is increased, as has already been described.

If the ground conditions at greater depths change to softer layers again, such as sand layers, the ratio of the amounts of fuel supplied by the injection devices 52 and 68 can be adapted accordingly. Individual adjustment of the function and mode of operation of the diesel pile hammer 10 to different ground conditions that change per se is thus possible, wherein good and complete combustion of the diesel oil is ensured.

When working in hard ground layers in which the principle of impact atomisation is used, the high-pressure injection device 52 is preferably operated with a small amount of fuel with every working cycle. The fuel pump 53 of the high-pressure device 52 therefore supplies the high-pressure injection nozzle 54 with a minimum amount of fuel with every working cycle. This prevents the inject-ion nozzle 54, as a rule constructed so as to be very fine, of the high-pressure injection device 52 from clogging as a result of combustion residues or other impurities, such as lubricant residues, and no longer functioning.

In a modification it is possible to use only a single pump to provide pressurised fuel, which pump is used in equal measure for the high-pressure injection and the low-pressure injection (optionally via a pressure reducer or a regulator).

And in a further modification a fuel amount controller may be dispensed with during operation if a particularly simply constructed diesel ram is desired and/or the changes in load are small. 

1. A diesel pile hammer comprising a cylinder, a piston slidably guided in the cylinder, an impact piece that is slidably guided in the cylinder and in the operating position of the diesel pile hammer is arranged below the piston, a working compartment which is axially delimited by an end face, located inside the cylinder, of the impact piece and an end face of the piston, a fuel supply device through which a predefined amount of fuel, can be introduced into the working compartment with every working cycle, wherein the fuel supply device is constructed in such a way that the fuel is injected into the working compartment in a first mode of injection as an atomised fuel mist and in a second monde of injection as a fuel jet.
 2. The diesel pile hammer of claim 1, wherein the fuel supply device designed in such a way that the fuel mist of the first mode of injection flows into the working compartment in the vicinity of the end face of the impact piece substantially vertically to the direction of movement of the piston.
 3. The diesel pile hammer of claim 1, wherein the fuel supply device is designed in such a way that the fuel jet of the second mode of injection obliquely strikes the piston-side end face of the impact piece.
 4. The diesel pile hammer of claim 1, wherein the fuel supply device comprises at least one high pressure injection nozzle and at least one low-pressure injection nozzle, to which, via one pipe in each case and by way of at least one fuel pump, of which the inlet communicates with a fuel tank, the predefined amount of fuel can be supplied with every working cycle of the diesel pile hammer.
 5. The diesel pile hammer of claim 4, wherein at least one fuel pump of the fuel supply device is constructed in such a way that the amount of fuel supplied to a high-pressure injection device in each case and the amount of fuel supplied to a low-pressure injection device in each case can be adjusted.
 6. The diesel pile hammer of claim 4, wherein the fuel pump can be controlled or actuated by way of the dropping piston.
 7. The diesel pile hammer of claim 4, wherein the fuel supply device is constructed in such a way that it supplies the high-pressure injection nozzle with a minimum amount of fuel with every working cycle.
 8. The diesel pile hammer of claim 1, wherein the end face of the piston delimiting the working compartment is stepped by a circumferential, radially external step.
 9. The diesel pile hammer according to claim 1, wherein during a third mode of injection, the fuel is injected into the working compartment of the cylinder as both an atomised fuel mist and as a fuel jet.
 10. The diesel pile hammer of claim 4, wherein the predefined amount of fuel supplied with every working cycle of the diesel pile hammer is adjustable.
 11. The diesel pile hammer of claim 2, wherein the fuel supply device is designed in such a way that the fuel jet of the second mode of injection obliquely strikes the piston-side end face of the impact piece
 12. The diesel pile hammer of claim 2, wherein the fuel supply device comprises at least one high pressure injection nozzle and at least one low-pressure injection nozzle, to which, via one pipe in each case and by way of at least one fuel pump, of which the inlet communicates with a fuel tank the predefined amount of fuel can be supplied with every working cycle of the diesel pile hammer.
 13. The diesel pile hammer of claim 3, wherein the fuel supply device comprises at least one high pressure injection nozzle and at least one low-pressure injection nozzle, to which, via one pipe in each case and by way of at least one fuel pump, of which the inlet communicates with a fuel tank the predefined amount of fuel can be supplied with every working cycle of the diesel pile hammer.
 14. The diesel pile hammer of claim 12, wherein at least one fuel pump of the fuel supply device is constricted in such a way that the amount of fuel supplied to a high-pressure injection device in each case and the amount of fuel supplied to a low-pressure injection device in each case can be adjusted.
 15. The diesel pile hammer of claim 5, wherein the fuel pump can be controlled or actuated by way of the dropping piston.
 16. The diesel pile hammer of claim 5, wherein the fuel supply device is constructed in such a way that it supplies the high-pressure injection nozzle with a minimum amount of fuel with every working cycle.
 17. The diesel pile hammer of claim 6, wherein the fuel supply device is constricted in such a way that it supplies the high-pressure injection nozzle with a minimum amount of fuel with every working cycle.
 18. The diesel pile hammer of claim 2, wherein the end face of the piston delimiting the working compartment is stepped by a circumferential, radially external step.
 19. The diesel pile hammer of claim 13, wherein the end face of the piston delimiting the working compartment is stepped by a circumferential, radially external step.
 20. The diesel pile hammer of claim 4, wherein the end face of the piston delimiting the working compartment is stepped by a circumferential, radially external step. 